Fluorinated ionic molecule enables synergistic surface passivation and charge balancing for efficient green
Di Shen1, Jianhao Ding1, Yuhang Tan1
1Key Laboratory of Advanced Technologies of Materials (Ministry of Education), School of Materials Science and Engineering, Southwest Jiaotong University, Chengdu 610031, PR China.
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Perovskite quantum-dot light-emitting diodes (PeQLEDs) remain limited by coupled surface and interfacial losses: labile ligand binding produces trap-rich perovskite quantum dot (PeQD) surfaces while unbalanced carrier injection accelerates interfacial charge accumulation and nonradiative recombination. Here, triphenylmethylium tetrakis(pentafluorophenyl)borate (TrTPFB) is introduced as a fluorinated ionic molecule to synergistically regulate both the surface coordination and charge-injection behavior of FAPbBr₃ PeQDs. Density functional theory (DFT) calculations reveal pronounced charge redistribution between TrTPFB and the PeQD surface. Experimental results show that the fluorinated tetrakis(pentafluorophenyl)borate (TPFB-) anion and the positively charged triphenylmethylium (Tr+) cation cooperatively stabilize the surface coordination environment and suppress trap-mediated nonradiative recombination. TrTPFB also induces p-type electronic modulation of the PeQD film, shifts the Fermi level toward the valence band, lowers the hole-injection barrier, and mitigates interfacial charge accumulation. Consequently, The combined operation of these mechanisms significantly improves the photoluminescence quantum yield (PLQY) of perovskite films to an impressive 98.50%. The corresponding green PeQLED achieves a peak external quantum efficiency of 17.50%, a maximum luminance of 80,859.28 cd m-2, and an approximately threefold increase in the average T₅₀ lifetime compared with the control device. This work establishes a fluorinated ionic molecular strategy that integrates surface passivation and charge-injection regulation for efficient and stable PeQLEDs.
